Engine starting apparatus with generator separately excited during starting



y 1953 B. H. SHORT ETA ENGINE START ING APPARATUS WITH GENERATOR SEPARATELY EXCITED DURING STARTING Filed Oct. 30, 1950 4. W 7 I I To IGNITION a; 6;

INVENTORS I Bkooks ll. SHORT nae HTTORNE Ys Patented May 26, 1953 ENGINE STARTING APPARATUS WITH GEN ERATOR SEPARATELY EXCITED DURING STARTING Brooks H. Short, Anderson, and John W. Dyer, Pendleton, Ind., assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application October 30, 1950, Serial No. 193,011

2 Claims.

This invention relates to the control of the engine starter of vehicle propelling internal combustion engines, particularly an engine which idles at very low speed.

An object of the present invention is to prevent inadvertent operation of the engine cranking electric motor while the engine is self-operative and particularly while the engine is running at a very low idling speed. This object is accom plished by an electrical system which includes a generator driven at variable speed by the vehicle propelling engine. Instead of using a wholly self-excited generator as has been the practice heretofore in automotive electrical systems, the generator of the present system has a shunt field winding which is separately excited by the storage battery until the generator attains a voltage suflicient for battery charging; and the present system includes apparatus which becomes effective to prevent use of the engine cranking motor when the generator voltage attains a value intermediate between the value at maximum engine cranking speed and the value at minimum engine idling speed. In the disclosed embodiment of the invention this apparatus includes a relay switch having a magnet coil which is connected with the generator terminals when the motor controlling switch is closed, said relay switch being constructed to operate when generator voltage is above the value attained at maximum cranking speed and below the value attained at minimum engine idling speed. For example, in a system for charging a six-volt storage battery, if the generator voltage attained at maximum cranking speed is about 2 volts and the generator voltage attained at minimum engine idling speed is about 4.5 volts, the relay switch would be constructed to operate at about 3.2 volts. Separate excitation of the generator field before the generator is connected with the storage battery by a cut-out relay enables the generator to produce, at maximum engine cranking speed and minimum engine idling speed, voltages such that their differential is a substantial amount as contrasted with the very low differential for a self-excited generator whose voltage rise in same low speed range is very gradual since that rise is initiated solely by residual magnetism. The substantial voltage differential which the separately excited generator provides in the low speed range enables the use of apparatus which can be relied upon not to interfere with the engine starting operation and to prevent inadvertent use of the engine starter while the engine is running even at low idling speed.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

The figure of the drawing is a wire diagram of the present invention.

Referring to the drawing, a generator 1 is connectible through a reverse current or cut-out relay COR with a battery 2. Generator I has a shunt field winding 3 which is separately excited from the battery 2 by closure of the ignition switch 4. Shunt field current is controlled by voltage regulator 5 having normally closed contacts 6 by-passing a resistance 1 connecting one end of the winding 3 with ground. Separation of contacts 6 is under control by magnet coil 9 responsive to a generator voltage which the regulator is set to control. When geenrator voltage exceeds a certain value, an armature 8 is attracted to separate the contacts 6 whereupon resistance 1 becomes effective to reduce generator field current.

The engine is started by operation of a starting motor I!) having a series field winding ll connectible with battery 2 by engagement of a contact l2 with contacts [3 and I4 of a relay R3. Contact I2 is maintained spaced from contacts I3 and I 4 by a spring and contact 12 is moved into engagement with contacts l3 and M in the response to energization of relays magnet coils I6 and i1. Coil I6 has relatively few turns of relatively coarse wire and coil H has a relatively large number of turns of relatively fine wire.

The junction [8 of coils l6 and I1 is connected by wire IS with a frame 26 of a relay B2. Frame supports and is electrically connected with a leaf spring 2| carrying a contact 22 normally separated from a contact 23 connected with the battery 2. The leaf spring 21 supports an armature 24 facing a core 25 surrounded by a winding 26, one end of which is connected with the battery 2 when ignition switch Cl is closed. The other end of coil 26 is connected with a contact 30 normally engaged by a contact 3! of a relay RH. Contact 3| is carried by a leaf spring 32 supported by and electrically connected with a frame 33 of a relay RI. Leaf spring 32 supports an armature 34 facing a magnet core 35 attached to the frame 33, the core is surrounded by a magnet coil 36, one end of which is attached to core 35 and, hence, is electrically connected with frame 33. The other end of coil 36 is connected with a switch contact 41 of a manually operated normally open switch 40. By closing switch 40 against the action of a spring 42, a contact 43 connects contact 4! with a contact 44 connected with a wire 45 which connects regulator coil 9 with the non-grounded ter minal of generator Switch 40 has normally opened contact 46 which, when closed, bridges contacts 41 and 48 to connect frame 33 of relay R! with ground.

To start the engine a driver closes ignition switch 4 and switch 40. The following circuit is established: battery 2, ignition switch 4, coil 26 of relay R2, normally closed contacts 39 and 3i, spring blade 32, frame 33, of relay RI and switch contact 46 engaging contacts 4'! and 43. Coil 25 having been energized, contact 22 engages contact of relay R2 and the following circuit is established: battery 2, contacts 23 and 22, spring blade 2|, frame 26, wire l9, coil I! of relay R3 to ground, coil switch contact 13, held coil H, and starting motor id to ground. The motor It operates to crank the engine. When the engine becomes self-operative and while its speed is less than that required to cause the generator to develop a voltage suiiicient to cause the cutout relay COR to connect it with the battery and even before the generator attains a minimum idle speed, the speed of the generator will be such as to cause it to develop a voltage such that coil 36 of relay R! will be energized sufficiently to separate contact 3| from contact and coil 25 of relay 2;! will be deenergized and contact 22 will separate from contact 23 to open circuit coils l and ll of relay R3 thereby causing switch contact :2 to be opened by a spring id. The starting motor l0 will cease operating regardless of failure of the driver to release switch it as soon as the en ine became selfoperative. The operation of the engine starting motor it cannot be effected while the engine is running even at low idle speed. Closure of the switch ll) under those conditions will not cause operation of the starting motor Ill because relay R! would immediately separate its contact 3! from contact 38 because the voltage of generator i would then be in excess of that required for suiiicient energization of relay coil 36 to separate contact 3 i from contact 39 before the engine had attained minimum idle speed. Relay R! is set to open its contacts when the voltage of the generator is between the value at maximum engine cranking speed, for example 2 volts, and the value at the lowest engine idling speed, for example 4.5 volts. The relay is set to open its contacts preferably about 3.2 volts.

If it should happen that the generator is not functioning to produce the required minimum voltage to open the contact of relay RI, discontinuance of the starting operation can be effected by opening switch 40. When the starting operation is not discontinued automatically, the driver will know that the generator is not functioning properly and will drive to a service garage where the generator can be put in proper condition.

The armature shaft of the starting motor In can be connected with the engine flywheel gear by a pinion which is automatically shifted by virtue of rotation of the armature shaft or the starting motor may be connected with the flywheel gear by a pinion which is shifted by move- 4 ment of an armature eil'ected by energization of coils IB and ll of relay R3, the retraction of the magnetically shifted pinion being effected by a spring when coils IS and H are deenergized, as disclosed more fully in the patent of John B. Dyer, 2,302,687, issued November 24, 1942.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An electrical system for automotive vehicles comprising an engine driven generator; a storage battery; a cut-out relay for connecting the generator with the battery when the generator attains a voltage sufficient for battery charging, said generator having a shunt field winding; an electric motor for cranking the engine; a plurality of manually operated switches for controlling operation of the motor; a circuit including one of the switches for connecting the field winding directly with the battery whereby the generator is separately excl until the generator voltage exceeds battery voltage; and means for preventing operation of the starting motor while the engine is self operative when all of the switches are closed, said means including all of the switches and normally closed contacts of a relay, said relay having a coil; and a circuit established by closure of all of the switches for connecting the relay magnet coil with the generator, said relay being responsive to separate its contacts when the generator voltages attain a certain value.

2. An electrical system for automotive vehicles comprising an engine driven generator; astorage cattery; a cut-out relay for connecting the gencrater with the battery when the generator attains a voltage sufficient for battery charging, said generator having a shunt field winding; an electric motor for cranking the engine; a manually operated ignition switch and a pair of auxiliary switches manually operated. by a common actuator for controlling ope 'ation of the motor; a circuit including the ignition switch for connecting the field winding directly with the battery whereby the generator is separately excited until generator exceeds battery voltage; means for causing the motor to be connected with the battery and including the ignition switch and the auxiliary switches and normally closed contacts of a relay, said relay having a magnet coil; and a circuit established during the closure of the auxiliary switches for connecting the relay magnet coil with the generator terminals, said relay being responsive to open its contacts when generator voltage attains a certain value, said circuit being open when one of the auxiliary switches is open.

BROOKS I-l. SHORT. JOHN W. DYER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,828,514 Spivey Oct. 30, 1931 1,941,483 Doman Dec. 26, 1933 2,062,970 Dyer Dec. 1, 1936 2,302,687 Dyer Nov. 24, 1942 

